Why was his friend so nice to me?

I’ve only met him once and he didn’t really speak to me at all the first time we met. My boyfriend came over to look at my car the other day and he brought his roommate/friend with him. My boyfriend left to test drive the car down the road and his friend started talking to me. Before I walked outside I heard his friend say “I’m surprised your girlfriend isn’t here.”

After my break left he was Asking me how I been and talking about my bf’s kid and how sweet she is. Told me his ex wife looks old lol and how he had no intentions of getting to know her. He talked to me more than my own boyfriend did. He also kept lifting his shirt up around me. I just thought it was weird for him to up and start talking to me right after he left when he didn’t speak to me the first time I met him.

By the way I don’t even know if my boyfriend is even my boyfriend anymore cause he told me the other day he don’t know if we’re a couple or not. I do know the past 2 times we’ve had sex he’s ghosted me. And we’ve only done it once within 3 weeks. Maybe his friend was sweet to me cause he knows something I don’t?